Search results for "Online"
showing 10 items of 4526 documents
Talking about Migration: the Online Discourse of Some Italian Political Party Leaders
2020
The aims of the article are to deconstruct the frames of migration crisis embedded on the official web sites, social networks and blogs belonging to the leaders of the main Italian political parties, positioned on different points of the left or right political spectrum, in the period 2015-2016. According to the relevance of the Italian context, we are also going to study the position of a party that can be considered a post-ideological movement that represents itself as outside of a traditional political spectrum: the Five-star Movement. We analysed text, images and videos published on the Internet 2.0 sites in order to show the legacy of colonialism that was characterized by the ambivalen…
Arte e diritti degli animali: una coalizione di protesta eterogenea contro la promozione pubblica di Nitsch
2016
L’intervento analizza il caso di una petizione online e l’evoluzione della protesta, sui social network e nel territorio, all’interno di una composita coalizione sociale. Si tratta della petizione (Change.org 2015), contro la sponsorizzazione da parte del Comune di Palermo della mostra dell’esponente dell’azionismo Viennese Hermann Nitsch che secondo promotori e firmatari violerebbe con le sue performance la Dichiarazione Universale dei Diritti degli Animali (Unesco 1978). La petizione che in breve tempo ha raccolto oltre 70.000 firme rappresenta un interessante esempio di mobilitazione online che travalica i confini nazionali, la protesta, infatti, era partita a Città del Messico un anno p…
Moving from an Online Petition to an Informal Network of Artist-Activists: Protest and Participation in Palermo
2016
This paper will concern with the new forms of political participation starting from the study of the case of the online petition against the public sponsorship by the local municipality (Comune di Palermo) of the exposition by Hermann Nitsch known as an exponent of Viennese Actionism. The online petition (posted on Change.org and spreading on the social networks) that in short time has almost collected more than 70.000 signatures can represent an interesting example of online mobilisation and above all a case of creation – as unexpected effect – of an a non-profit informal network of artists able to create new forms of solidarity, mutualism and resistance against the progressive colonizatio…
MAST solution of irrotational flow problems in 2D domains with strongly unstructured triangular meshes
2010
A new methodology for the solution of irrotational 2D flow problems in domains with strongly unstructured meshes is presented. A fractional time step procedure is applied to the original governing equations, solving consecutively a convective prediction system and a diffusive corrective system. The non linear components of the problem are concentrated in the prediction step, while the correction step leads to the solution of a linear system, of the order of the number of computational cells. A MArching in Space and Time (MAST) approach is applied for the solution of the convective prediction step. The major advantages of the model, as well as its ability to maintain the solution monotonicit…
An experimental investigation of the nonlinear refractive index (n2) of carbon disulfide and toluene by spectral shearing interferometry and z-scan t…
2003
International audience; The recently proposed spectral shear interferometry and the well-known z-scan techniques were employed for the determination of the nonlinear refractive index n2 of CS2, toluene and fused silica. The determined n2 values by both techniques were found to be in very good agreement. In addition, the role of the repetition rate of the laser is also investigated revealing its importance for the correct determination of both the size and the sign of the nonlinearity.
Shock formation in the dispersionless Kadomtsev-Petviashvili equation
2016
The dispersionless Kadomtsev-Petviashvili (dKP) equation $(u_t+uu_x)_x=u_{yy}$ is one of the simplest nonlinear wave equations describing two-dimensional shocks. To solve the dKP equation we use a coordinate transformation inspired by the method of characteristics for the one-dimensional Hopf equation $u_t+uu_x=0$. We show numerically that the solutions to the transformed equation do not develop shocks. This permits us to extend the dKP solution as the graph of a multivalued function beyond the critical time when the gradients blow up. This overturned solution is multivalued in a lip shape region in the $(x,y)$ plane, where the solution of the dKP equation exists in a weak sense only, and a…
Numerical study of the Kadomtsev–Petviashvili equation and dispersive shock waves
2018
A detailed numerical study of the long time behaviour of dispersive shock waves in solutions to the Kadomtsev-Petviashvili (KP) I equation is presented. It is shown that modulated lump solutions emerge from the dispersive shock waves. For the description of dispersive shock waves, Whitham modulation equations for KP are obtained. It is shown that the modulation equations near the soliton line are hyperbolic for the KPII equation while they are elliptic for the KPI equation leading to a focusing effect and the formation of lumps. Such a behaviour is similar to the appearance of breathers for the focusing nonlinear Schrodinger equation in the semiclassical limit.
Observation of Optical Undular Bores in Multiple Four-Wave Mixing
2014
International audience; We demonstrate that wave-breaking dramatically affects the dynamics of nonlinear frequency conversion processes that operate in the regime of high efficiency (strong multiple four-wave mixing). In particular, by exploiting an all-optical-fiber platform, we show that input modulations propagating in standard telecom fibers in the regime of weak normal dispersion lead to the formation of undular bores (dispersive shock waves) that mimic the typical behavior of dispersive hydrodynamics exhibited, e.g., by gravity waves and tidal bores. Thanks to the nonpulsed nature of the beat signal employed in our experiment, we are able to clearly observe how the periodic nature of …
Incoherent Dispersive Shocks and Spectral Collapse
2014
We predict the existence of incoherent dispersive shock waves and collapse-like singularities that occur in the spectral evolution of incoherent optical waves propagating in a noninstantaneous nonlinear medium.
Incoherent dispersive shocks in the spectral evolution of random waves
2013
We predict theoretically and numerically the existence of incoherent dispersive shock waves. They manifest themselves as an unstable singular behavior of the spectrum of incoherent waves that evolve in a noninstantaneous nonlinear environment. This phenomenon of "spectral wave breaking" develops in the weakly nonlinear regime of the random wave. We elaborate a general theoretical formulation of these incoherent objects on the basis of a weakly nonlinear statistical approach: a family of singular integro-differential kinetic equations is derived, which provides a detailed deterministic description of the incoherent dispersive shock wave phenomenon.